Power Up; Power Key; Charger; External Supply Source Is Detected - Nokia 7088 Troubleshooting Manual

7088 (Flower)
Base band Description and Troubleshooting

Power Up

The mobile terminal can use the power key and a charger to power up.

Power Key

When the power key is pressed, the PM enters the power-up sequence. Pressing the
power key causes the KPADPWR_N pin ("PHONE_ON" net in schematic) to GND.
The power key is directly connected to the PM. This means that when the power key
is pressed, an interrupt will be generated to the MSM in order to power on the MCU.
The MCU reads the PM IC's interrupt register and notifies that it is a KPADPWR_N
interrupt. The MCU reads the status of the KPADPWR_N pin using the PM's (SBI)
control bus. If the KPADPWR_N stays low for a certain time, the MCU accepts this
as a valid power-on state and continues the software baseband initialization. If the
power key does not indicate a valid power-on situation, the MCU powers off the base
band.

Charger

Charging is controlled by the start-up charging circuitry in order to detect and start
charging in cases the main battery is empty and the PM has no supply.

External supply source is detected

If a valid source is applied to VCHG (pin 1 of PM IC, "VEXT_DC" net) and the battery
voltage of VPH_PWR exceeds PM's valid UVLO (2.5V) threshold, the power-on
sequence of PM is initiated and its internal regulators are enabled. UVLO is the
minimum voltage required for PM6610 operation. If the entire power-on sequence is
successful, the appropriate interrupt from PM will be sent to the MSM. Once the
battery voltage rises above 3.0V (min. MSM operation voltage), code starts running
on MSM. The MSM reads PM registers to identify the power source and whether
battery charging is required. If a valid supply voltage is applied while the PM IC is on,
the power-on sequence is skipped. A charging sequence will then be initiated.

Power Off

While the PS_HOLD signal from the MSM is high and the PM IC is in one of its
power-on states, the PM continually monitors three events that could trigger a
power-off sequence:
The MSM drives the PS_HOLD signal low responding to the pressing of the
keypad power button.
Battery voltage drops below power off threshold (Battery voltage < 3.3 V).
The PM IC die temperature exceeds its "severe" over-temperature threshold.
Page 8 © 2006 Nokia Corporation Company Confidential Issue 1 12/2006